Sunday, April 10, 2011

Most of you have had a version of this experiment in your lifetimes...but probably not until you were of legal drinking age. Alcoholic beverages, even beers, come in all sorts of densities, so they're easy enough to layer into a single drink; it's a common enough cocktail technique that bartending websites offer alcohol density charts.

The usual method for creating a kid-friendly version of this experiment involves adding progressive amounts of sugar to a flavored drink mix, but since there's so much news about food dyes recently, I thought maybe I'd try it using juice concentrate. The science behind this density column is simple: drinks containing more sugar are more dense.

In this case, instead of adding sugar, we used orange juice concentrate and just added less water than usual (we approximated the amount for a simple two-layer column) to make our base - however, if you want to teach your child about the benefits of label-reading, have them compare the sugar content of different juices and layer them lowest to highest (you can cheat by diluting slightly with water as well.) Make sure your labels compare the same serving size!

Then, using a spoon to reduce the force of the pour and keep the juices from mixing, we added the second juice (we used a cranberry-pomegranate blend)

Although the two mixtures were miscible, we did wind up with a nice (if slightly blurry) division between the two juices...you can keep adding layers by changing the level of dilution of juice.

The science here isn't really that hard to grasp: things that are more dense have more mass per unit of volume, meaning, basically, a more dense substance has more stuff in it. Less dense fluids float on more dense fluids if they do not mix; the key here is to keep the two miscible (mixable) liquids from mixing.

For our regular readers, Sundays with Sparky will return in two weeks on April 24...but look for a special Sundays/Food Desert Project mashup post on Wednesday the 13th!